Set in the Rainbow Islands, Bub and Bob are now under the shadow of an evil record company who is polluting the ecosystem with a constant, mass-produced musical dirge. This cacophony causing the flora to wilt and the fauna to mutate into aggressive enemies. Only Bub and Bob have the experience to take on the record company and its seven bosses, setting the stage for an entirely new adventure.

This game is also known as New Rainbow Island: Hurdy Gurdy Daibouken!! in Japan.